All six plants studied (Senna petersiana, Terminalia sericea, Cassine transvaalensis, Elephantorrhiza burkei, Rauvolfia caffra and Anredera cordifolia) proved to have considerable antibacterial activity. The water extracts of five of the six plants tested, showed activity against Bacillus pumilis, B. subtilis and Staphylococcus aureus respectively. Water extracts from S. petersiana showed a significant antibacterial activity by inhibiting all Gram-positive and two Gram-negative bacteria. A cytotoxicity assay of three plants (S. petersiana, T. sericea and A. cordifolia) on primary vervet monkey kidney ceelsl showed that A. cordifolia was the least cytotoxic extract with an ID50 value of 1.560 mg/ml. Both S. petersian and T. sericea showed an ID50 value of 0.024 mg/ml. Cytotoxicity as determined in this study does not necessarily mean that the active compound which can be isolated from these plants will also be toxic. Antiviral activity of S. petersiana, T. sericea and A. cordifoli crude extracts were investigated against herpes simplex virus type I at the non-toxic concentrations. Both T. sericea and A. cordifoli extracts showed to be non-active against HSV -I, but S. petersiana showed a 20 % reduction in replication of the virus after the sixth day of the experiment. Because of the sensitivity and instability of compounds in the root extract of S. petersiana, it was very difficult to isolate any pure compound. Bioassay-guided fractionation of the seeds of S. petersiana resulted in the isolation luteolin. Its structure was identified and confirmed through spectroscopic methods including IH, BC, UV, HMBC and HMBQ. An antibacterial assay of luteolin isolated from the seeds of S. petersiana showed activity against Baccilus cereus, B. pumilis, Streptococcus aureus and Staphylococcus areus at the concentration of I mg/ml. In the assay to assess the possible antiviral activity of luteolin against herpes simplex type I virus, 50% of the virus was inactivated at the concentration of 250 μg/ml. The results of this study have shown that it is possibl4e that the extracts studied, can provide humankind with valuable agents of potential use in the treatment of herpes and some bacterial species.
Dissertation (MSc ( Plant Physiology))--University of Pretoria, 2006.